Cramer: The winner of the Rite Aid and Walgreens deal

It's that time again! Jim Cramer rang the lightning round bell, which means he gave his take on caller favorite stocks at rapid speed:

AK Steel Holding: "AK Steel, not my favorite. I like Nucor because I love a good balance sheet. I know steel's letter X is hot. I just want to stick with the one that has been so good for so long, which is Nucor."

Exelixis, Inc: "We liked it much, much lower. It's got a great speculative book of business, but remember it is speculative. That is really important I don't want anyone to confuse this with Merck."

Rite Aid: "My charitable trust owns Walgreens. That is the winner, either way because they just negotiated the price down for Rite Aid. I just think don't buy. Don't fool around with it because we don't know what the FTC is going to do here."

Box Inc: "Aaron Levie [CEO] is doing a really good job. That was a very good quarter. Next quarter I think is going to be even better … by the way, the market cap is very small there. So it's OK. $17 goes to $20.

American Airlines Group: "American Airlines is at the right level. I know that the Bernstein upgrade caught people by surprise. I think that American is good. I like Alaska and I like Southwest, but I think American, that's a good level to get involved."

Corning Incorporated: "Corning has had a big run. I know they are deeply involved with Apple — which you know I say own don't trade — but Corning has had a big run. That concerns me because it has been a hit-or-miss stock. I'm going to say stay away from it at this level.